Control of yarn tensions

ABSTRACT

A method and device for supplying yarn to yarn treating processes is provided in which the yarn supplied is placed under a desired tension. The device includes two spaced delivery rollers about which the yarn runs in several windings. Interposed the rollers are three braking surfaces disposed parallel to the roller axes. The yarn passing between the rollers passes alternately above and below such surfaces and in slidable contact therewith, the middle surface is movable relative to the surfaces disposed on either side thereof whereby a variable tension may be applied to the yarn engaged, depending upon the disposition thereof.

[451 Oct. 14, 1975 CONTROL OF YARN TENSIONS [76] Inventor: Karl Bous,Sternstr. 74, 56

Wuppertal 2, Germany 22 Filed: Sept. 19, 1973 21 Appl. No.: 398,690

[30] Foreign Application Priority Data Sept. 19, 1972 Germany 2245869[52] US. Cl 242/47.01; 66/132 R; 242/47.09 [51] Int. Cl. 8651-1 51/20[58] Field of Search 2,658,367 11/1953 Shortland ..66/132 PrimaryExaminerStanley N. Gilreath Attorney, Agent, or FirmNeuman, Williams,Anderson & Olson [5 7] ABSTRACT A method and device for supplying yarnto yarn treating processes is provided in which the yarn supplied isplaced under a desired tension. The device includes two spaced deliveryrollers about which the yarn runs in several windings. lnterposed therollers are three braking surfaces disposed parallel to the roller axes.The yarn passing between the rollers passes alternately above and belowsuch surfaces and in slidable contact therewith, the middle surface ismovable relative to the surfaces disposed on either side thereof wherebya variable tension may be applied to the yarn engaged, depending uponthe disposition thereof.

3 Claims, 5 Drawing Figures US. atem 0d. 14, 1975 Sheet 1 of 3 3912,18

US. atant 0a. 14, 1975 Sheet 2 of3 3,912,18

CONTROL OF YARN TENSIONS The invention relates to a method and a devicefor supplying and tensioning yarns during winding or other yarntreatment processes with an adjustable thread tension which remainsconstant throughout the winding step.

In yarn treatment, an adjustable but constant yarn tension is in mostcases the prerequisite for a satisfactory output of the goods produced.However, since yarn tension is dependent on several factors, such as thespeed of removal, the diameter and type of the outlet members, theconstitution of the yarns and many other factors, before the actualthread brakes, so-called yarn supply systems, fournisseurs or yarnstores are often used, which partially eliminate tension differenceswhich arise when removing the yarn and if necessary allow the yarn to betreated with a lower thread tension.

It is necessary to differentiate between supply systems with positiveintroduction of yarn, which are only used in certain cases, and thefrequently-used, so-called slip supply systems. It is the purpose ofsupply systems with a positive introduction of yarn in particular tokeep constant certain yarn sections between two or several supplysystems, e.g. when producing continuous strips of yarn. Yarn storagedevices are frequently used with such textile machines when the removalof yarn is often interrupted or takes place at various speeds, e. g. onknitting or weaving machines.

It is the main task of the slip-supply systems, which are usually usedon winding machines, to reduce the tension differences arising whenremoving the yarn from the outlet member and e.g. to allow the windingor softer rollers. The requirement of reducing the yarn tension andpartially compensating the thread tension can be fulfilled easily byslip-supply systems. However, in order to keep yarn tension exactlyconstant, thread brakes, advantageously compensatory thread brakes, areprovided, which balance the tension differences up to a certain limit,but at the same time increase yarn tension again, which in many cases isundesirable.

It is the aim of the invention to lead the yarn to the correspondingdevice with an adjustable and, if necessary, very low thread tension andat the same time to keep constant thread tension during the entireoperating process by means of only one controllable supply system. Oneembodiment enables the yarn to be introduced automatically into thesupply system simultaneously, which is very important in the progressiveautomation of yarn treatment machines, since until now the yarn couldonly be guided through the supply rollers of the supply system by hand.

Further embodiments enable yarn tension to be controlled by theconnected device and/or the introduction of yarn to be stopped for ashorter or longer time or to be quickened up to proceed at high speedsof removal and upon breakage of a thread to stop the supply systemand/or the device working together with the supply system.

This is achieved in accordance with the invention in that the supplysystem, which consists of one supply roller and at least one rotating orstationary guide roller, or also of two driven supply rollers, isequipped with one or more braking levers which rest on all or some ofthe coils of the yarn which is being guided via the supply system and,according to the thread tension,

the one or more levers increase or reduce the size of the looping angleby means of braking elements provided and thus balance out tensiondifferences, whereby the initial tension of the yarn can be regulated bythe peripheral speed of the supply rollers and the pressure of thebraking pins resting on the yarn coils and determining the loopingangle, and it is compensated by feelers at the entry and/or exit of theyarn from the supply system by the braking lever and braking pins. Onthe other hand, the braking pins can be connected to the machine bymeans of braking levers and rods or other devices, the machine itselfdetermining the required yarn tension and/or temporarily stopping thesupply of yarn without having to stop the drive of the supply rollers.

Further features of the invention are described below with the aid ofthe accompanying drawings in which several preferred embodiments areillustrated in perspective or partially schematically. The features tobe seen from the drawings can be used alone or in any combination inother embodiments of the invention.

FIG. 1 shows a perspective view of a supply system consisting of adriven supply roller, a guide roller and a braking lever;

FIG. 2 shows a perspective view of a supply system equipped with acompensatory lever and a yarn tension feeler;

FIG. 3 shows a front view of a supply system consisting of two drivensupply rollers, braking elements and a compensatory lever;

FIG. 4 shows the supply system of FIG. 3 in plan view; and

FIG. 5 shows a supply system for compensating the yarn tensiondifferences with braking and compensatory elements at the entry and exitof the supply system, in front elevational view.

In FIG. 1 is illustrated a perspective view of a supply systemconsisting of a driven roller, one or more guide rollers and a threadbrake lever, which system itself compensates the yarn tension.

The yarn, coming from an outlet spool, a cop or a strand, is guidedaccording .to the type of yarn and the desired reduction in yarn tensiononce or several times about a supply roller 2, which is driven in thedirection of the curved arrow and about the guide rollers 3, which arerotatably mounted on a support pin 4 or can be fixed thereon, and theyarn is then led to a winding point which is not illustrated or toanother device for further treatment of the yarn. The guide rollers 3are advantageously provided with grooves 5 which determine the distancesbetween the yarn windings on the supply system. The individual guiderollers can however also be replaced by a thread guide pin provided withgrooves which guide the thread windings.

In many cases, however, it is more advantageous to use a smooth threadguide pin or a multi-pulley roller which is made to revolve by the yarn,whereby the distance between the yarn windings on the supply device canbe adjusted by inclining the thread guide pin or the pulley rollertowards the axis of the driven supply roller.

A brake lever 6 rests with its braking pin 7 on all or on one only ofthe yarn windings guided about the supply system, the pin 7 being madeof a material of high surface hardness and which has a lower or highercoefficient of friction according to the type of yarn. The brake lever 6with the optionally interchangeable braking pin 7 is secured to alightly pivotable holder or mounting 10, together with weighting levers8 and 9.

The function of the device of FIG. 1 is as follows: The yarn 1 which isguided e.g. four times about the supply system is removed from theoutlet spool by the driven supply roller 2, whose peripheral speed, asusual with slip-supply systems, must be greater than the thread speed.The force of withdrawal of the yarn from the offwinding spool throughthe supply system is smaller or greater, depending upon the rate ofrevolution of the yarn about the supply system and the peripheral speedof the supply roller, and the yarn tension which is caused by the ballof threads or by other reasons is reduced to a greater or lesser extent,whereby at the same time the yarn tension differences arising duringwithdrawal are partially eliminated before winding of the yarn on to thetakeup spool by the known tensionbalancing effect of the slip-supplysystem.

The tension-balancing effect of the slip-supply system is only slight,however, and for this reason the braking pin 7 of the brake lever 6 isplaced on the yarn winding as they are guided about the supply system,aided by the weight of the counterbalanced braking weight 11 on thelever 8. Irrespective of the speed of withdrawal, the thread tension ofthe yarn being guided about the supply system and the pressure of thebraking pin on the yarn windings 12, the yarn is looped around thebraking pin with a smaller or greater looping angle, whereupon thethread tension in the yarn section 13 increases.

After the desired yarn tension has been set between the supply deviceand the winding point or the device for further treatment of the yarn bymeans of the counterbalance l1 and 14, i.e. the braking weightsdisplaceably attached to the weighting levers 8 and 9, respectively, theyarn tension in the yarn section 13 remains constant independently ofthe tension differences between the off-winding member and the supplysystem, since when the yarn tension between the offwinding member andthe supply system becomes greater or when the speed of withdrawal of theyarn becomes greater, e.g. through the winding point, the yarn tensionof the yarn windings about the supply system also increases, less yarnis wound around the breaking pin and its braking effect on the yarn isreduced, so that the yarn tension in the yarn section 13 remainsconstant.

In the opposite case, when the withdrawal tension of the yarn from theoff-winding member is smaller or when winding is at a lower speed, thethread tension of the individual yarn windings about the supply systemalso reduces, the braking pin engages deeper into the windings, itsbraking effect increases and the thread tension in the yarn section 13increases to the adjusted value. If, in an extreme case, the connecteddevice temporarily stops the withdrawal of yarn, the braking pin engagesso deeply into the yarn windings that it completely eliminates operationof the supply roller.

If, however, a greater braking effect is required because of a lowcoefficient of friction of the yarn or of the braking elements, it isadvantageous to arrange a further fixed braking pin 15 between thesupply rollers and the movable braking pin, which pin 15 is to beattached such that when viewed from the direction of movement of theyarn it comes into contact under the yarn windings 12 closely before themovable braking pin. As soon as the movable braking pin presses down onthe yarn coils e.g. when the yarn tension drops or when the withdrawalspeed is reduced, the yarn windings loop around the fixed braking pin 15also, and at the same time the looping angle of the yarn about themovable braking pin 7 becomes greater, so that there is a significantlygreater braking effect on the yarn and the tension differences arebalanced more quickly. There is an additional advantage, since thebraking pin 15 at the same time prevents alteration of the looping angleof the yarn coils about the driven supply roller.

If, however, rotatably mounted guide rollers or multipulley rollers mustbe used, and the additional braking effect of the looping angle aboutthe guide rollers cannot be dispensed with, a further braking pin 16 isto be provided between the movable braking pin and the rotatably mountedguide rollers, as illustrated in FIG. 1.

The combination of a movable braking pin with two counter-balances andtwo fixed braking pins, between which the yarn windings are pressed to agreater or lesser extent by the movable braking pin dependent on theyarn tension, can be applied to any section of the yarn windings beingguided about the supply system. e.g. even on the lower yarn runs 17,since in this case the looping angles of the yarn windings about thesupply roller and the guide rollers do not alter.

In certain cases, in order to avoid too great a yarn tension which iscaused by the braking pins and to be able to guide the yarn to thewinding point with very low yarn tension, the peripheral speed of thesupply roller should be greater than with conventional slip-supplysystems and it should also be possible to keep the pressure of thebraking pin 7 on the yarn windings very low, e.g. by adjusting thecounterbalance 14.

The supply system illustratedin perspective view in FIG. 2 isadditionally equipped with a yarn tension feeler 18, about which theyarn 19 coming from the supply system moves at an angle to a windingpoint which is not illustrated or to another device for furthertreatment of the yarn.

The yarn tension feeler is a bar 18 connected on the journal 22 to thebraking pin 23 by means of the compensatory lever 20 and the holder 21which is positioned so as to be easily pivotable. The desired yarntension is set e.g. by means ofa tension spring 25 interconnecting thelever 20 and a mounting member adjustably secured in an elongated slot24, the spring 25 pulling the tension feeler 18 in the direction of thearrow A, opposite to the direction of yarn tension. When the yarntension in the yarn section 19 becomes smaller, the yarn tension feeler18 is moved by the effect of the tension spring 25 further in thedirection A, and through the compensatory lever 20 and the holder 21,this movement is transferred to the braking pin 23, which presses intothe yarn windings 26 to a greater extent, so that the looping angle ofthe yarn windings 26 about the braking pin 23 increases and the yarntension in the yarn section 19 increases until the state of equilibriumhas been reached again between the spring force and the yarn tension.

In the opposite case, when the yarn tension in the yarn section 19becomes greater, the tension feeler 18 moves in the direction of thearrow B, the braking pin does not penetrate so far into the yarnwindings 26 and the yarn tension between the supply system and thewinding point reduces immediately to the value set. As already describedin connection with FIG. 1, the device of FIG. 2 can also be equippedwith further fixed braking pins and the force of the tension spring 25can be replaced by weights, permanent magnets or centrallycontrolledelectromagnets.

If, however, the yarn tension is to be controlled in dependence upon thetreatment process, the yarn tension control device of the connectedmachine engages on the compensatory lever by means of a rod which is notillustrated and/or displaces the journal of the tension spring in theelongated slot 24 in the direction A or B. Should however the yarntension-balancing effect of the tension feeler partially remain, theconnected device should only displace the journal of the tension springin the elongated slot 24.

FIG. 3 shows in front view and FIG. 4 in plan view a supply systemconsisting of two driven supply rollers, braking elements and a yarntension compensatory lever.

The supply rollers 27 and 28, between which are located the fixedbraking pins or braking surfaces 29 and 30, as well as the lever 32,which is pivotally mounted about the spindle 31, with the braking pin33, are rotated in the direction of the arrow at a speed which is about30% to 100% higher than the speed of withdrawal of the yarn from asupply device which is not illustrated.

On the lever 32 is also secured a tension spring 34, which by means ofthe lever presses the braking pin 33 between the braking surfaces 29 and30, whereby the tensile force of the spring 34 can be adjusted by movingthe knob 35 in the direction C or D. After lifting the lever 32, onwhich is secured the braking pin, the yarn 36, which is to be wound isguided once or several times about the supply rollers, so that the yarncomes to rest between the braking surfaces and the braking pin,whereupon it is guided by means of the thread guide roller 37 on thecompensatory lever 38, which is also secured to the lever 32, at anangle through the thread guide roller to the next winding point.

When using the device of FIGS. 3 and 4, according to the tension of theyarn 36, being removed from a spool, a cop or a strand and dependingupon the peripheral speed of the supply rollers and the winding speed,the yarn tension of the yarn windings about the supply system will belarger or smaller, and the braking pin will press the yarn coils to agreater or lesser extent between the braking surfaces through the effectof the tension spring.

After setting the desired yarn tension between the supply system and thewinding point by moving the knob 35, by simultaneous supplying andbraking of the yarn coming from the supply system, there is equilibriumbetween the spring tensile force and the yarn tension in the section 42.Due to yarn tension differences of the yarn being led to the supplysystem and/or due to yarn removal speed differences at the windingpoint, the thread guide roller 37 moves in the direction E or F. Thismovement is transferred by the compensatory lever 38 to the brakingparts so that the yarn tension in the section 42 remains constant.

Undesirable oscillatory movements of the compensatory lever which are inquick succession, can be avoided by a damping device, e.g. aneddy-currentvibration damper, which consists of an aluminium or copppersegment attached to the spindle 31, and the permanent magnet 41. A scale55 on the circular part 54 of the segment 40 allows the adjusted orexisting yarn tension to be read simultaneously.

On the spindle 31 firmly connected to the lever 32, further auxiliarylevers which are not illustrated can be attached, which also undergopivoting movement about the spindle, and if the given yarn tension valuedrops or increases, they disconnect the winding point or the connecteddevice for further treatment of the yarn and- /or the compensatorysupply system, e.g. by means of micro-switches. With the same or othermeans, which are actuated by the movement of the compensatory lever orof the segment 40, if the thread breaks, and the braking pin reaches thepoint G through spring force or if a yarn coil is formed on the supplyrollers and presses the braking pin in the direction H, the supplyand/or winding device is disconnected.

The spacing of the yarn windings or coils on the supply system can bedetermined by incling the two supply rollers relative to one another bymeans of the yarn guide pins 39 or a yarn guide comb.

In FIG. 5 a supply system in front view for compensating the yarntension with braking and compensatory elements at the entry and exit ofthe supply system.

The function of this device is essentially the same as that of thesupply system described in relation to FIG. 2, but additionally itallows the yarn tension oscillations to be sensed, which arise duringwithdrawal of the yarn 57 from the cop 58, before it enters the supplysystem through the thread guide roller 59 on the compensatory lever 60.The compensatory lever 60, the counterbalance lever 61 with theadjustable weight 62 and the braking lever 63 with the braking pin 64are secured to the holder 66 which is mounted on the journal 65 for easypivotal movement.

The braking pin 64 rests on the yarn section 67 of the windings of thesupply system, which consists of a supply roller 68 driven in thedirection of the curved arrow and the guide roller 69, and according tothe yarn tension in the yarn section 67, it presses the yarn coils togreater or lesser extent, whereby the looping angle of the yarn aboutthe braking pin and thus also its effect on the yarn coming from thesupply system is increased or reduced.

Similarly to the yarn tension compensatory device, whose breaking effectis determined by the yarn tension between the yarn removal member andthe supply system, a further mirror-image device is attached on thejournal 65, consisting of the holder 70, the thread guide roller 71, acompensatory lever 72 and a counterbalance lever 75 with itsinterchangeable braking pin 76.

However, the looping angle of the braking pin 76 through the yarnsection 77 of the windings about the supply system is determined by theyarn tension in the section 78, between the supply system and the devicefor the further treatment of yarn.

The device shown in FIG. 5 can be supplemented with further braking pinsto increase the yarn tension compensation, as described in connectionwith FIG. 2, and the counterbalances can be supplemented by springs,permanent or electro magnets, e.g. the braking pin 64 can be controlledby the yarn tension before or after the supply system and the brakingpin 76 by the yarn tension-control device of the connected device.

Because the parts or holders which are moved by the compensatory leversin FIGS. 2, 3 and 5 are equipped with levers on which are mountedrollers which are easily rotatable, the effect of friction between theyarn and the sensing levers can be dispensed with, so that thecompensatory effect of the devices is further improved.

In particular cases, the braking devices illustrated in FIGS. 3 and 4can be moved in an oscillatory manner in order to prevent the yarn fromcutting into the supply rollers or the braking parts.

The segment 40 in FIGS. 3 and 4 can be equipped with a pointer or amarking instead of a scale, which indicates the yarn tension on a scaleattached to the housing of the device.

I claim:

1. In a device for delivering yarn under desired, substantially constanttension to a zone of yarn use, the combination comprising two spaceddelivery rollers about which such yarn runs in several windings, atleast one of said delivery rollers being a drive roller, three brakingsurfaces disposed between said rollers and arranged parallel to eachother and to the delivery rollers, said yarn passing alternately aboveand below said three surfaces in constant slidable contact therewith inthe normal yarn delivering operation, the two outer braking surfacesbeing fixedly positioned; the middle braking surface disposed betweensaid outer surfaces being movable relative thereto; said movable middlesurface effecting various pressures on the yarn engaged thereby; saidpressures being dependent upon said movable middle surface dispositionrelative to said outer surfaces; means urging said movable brakingsurface in the direction of and between said fixed braking surfaces soas to increase the looping angle of the engaged yarn about said movablebraking surface and increase the tension of said yarn caused by saidmovable braking surface; increased tension in the yarn in the zone ofuse forcing said movable braking surface to withdraw from between thefixed braking surfaces whereby the looping angle of the engaged yarnabout said movable braking surface is decreased and the tension in saidyarn caused by said movable braking surface is decreased; said middlebraking surface comprising a brake pin, a pivotally movable leverfastened to said brake pin and movable about a pivot axis disposedparallel to said pin, an adjustable spring engaging said lever, saidspring effecting the movable brake pin contact pressure with such yarn,a compensation arm mounted on said lever having a thread guide rollarranged on its distal end, which roll is encircled in part by yarnemerging from the device in such a way that the yarn tension counteractsthe tension in said springengaging lever.

2. The device of claim 1 in which a pivotally movable segment ofaluminum or copper is mounted on said lever and moves relative to apermanent magnet so as to effect eddy-current vibration damping of saidlever and the movable brake pin mounted thereon.

3. The device of claim 1 in which a scale is connected to said movablebrake pin whereby the yarn tension corresponding to said brake pinangular disposition may be read at a glance.

1. In a device for delivering yarn under desired, substantially constanttension to a zone of yarn use, the combination comprising two spaceddelivery rollers about which such yarn runs in several windings, atleast one of said delivery rollers being a drive roller, three brakingsurfaces disposed between said rollers and arranged parallel to eachother and to the delivery rollers, said yarn passing alternately aboveand below said three surfaces in constant slidable contact therewith inthe normal yarn delivering operation, the two outer braking surfacesbeing fixedly positioned; the middle braking surface disposed betweensaid outer surfaces being movable relative thereto; said movable middlesurface effecting various pressures on the yarn engaged thereby; saidpressures being dependent upon said movable middle surface dispositionrelative to said outer surfaces; means urging said movable brakingsurface in the direction of and between said fixed braking surfaces soas to increase the looping angle of the engaged yarn about said movablebraking surface and increase the tension of said yarn caused by saidmovable braking surface; increased tension in the yarn in the zone ofuse forcing said movable braking surface to withdraw from between thefixed braking surfaces whereby the looping angle of the engaged yarnabout said movable braking surface is decreased and the tension in saidyarn caused by said movable braking surface is decreased; said middlebraking surface comprising a brake pin, a pivotally movable leverfastened to said brake pin and movable about a pivot axis disposedparallel to said pin, an adjustable spring engaging said lever, saidspring effecting the movable brake pin contact pressure with such yarn,a compensation arm mounted on said leveR having a thread guide rollarranged on its distal end, which roll is encircled in part by yarnemerging from the device in such a way that the yarn tension counteractsthe tension in said spring-engaging lever.
 2. The device of claim 1 inwhich a pivotally movable segment of aluminum or copper is mounted onsaid lever and moves relative to a permanent magnet so as to effecteddy-current vibration damping of said lever and the movable brake pinmounted thereon.
 3. The device of claim 1 in which a scale is connectedto said movable brake pin whereby the yarn tension corresponding to saidbrake pin angular disposition may be read at a glance.